In 2012, we, in collaboration with Dr. Yuan of Virginia Tech, performed a challenge study of the recombinant subunit P2-Wa VP8 candidate vaccine in gnotobiotic piglets. Five-day-old piglets were immunized intramuscularly 3 times with the P2-Wa VP8 vaccine with aluminum phosphate adjuvant. Seven days after the 3rd immunization, both vaccinated and mock-vaccinated control piglets were challenged orally with virulent human rotavirus Wa strain. The vaccine significantly delayed the onset of diarrhea and significantly reduced duration of diarrhea and cumulative diarrhea score. The amount of infectious Wa virus shed in stools of the vaccinated piglets was substantially lower (not statistically significant) compared to the controls.